1. Field of the Invention
The present invention relates to an automated sewing device for automatically sewing the curved ends of materials together. In particular, the invention is directed to an automated sewing device capable of sewing together the curved ends of thin contractible materials which naturally tend to curl.
2. Description of Prior Art
Basically, a trim cover assembly for a vehicle or automotive seat is formed by sewing together a peripheral cover material with a central cover material, wherein the central cover material is adapted to cover a central seating region of the seat on which a seat occupant's buttocks portion rests and the peripheral cover material is adapted to cover a peripheral vertical wall of the seat surrounding that central seating region of seat. In most cases, the central seating region of seat is of a generally ellipse or circular shape, and therefore, in conformity therewith, the corresponding central cover material is also of a generally ellipse or circular shape and thus has curved end portion. Accordingly, in the process of forming the trim cover assembly, end portion of the peripheral cover material should be aligned and sewn with such curved portion of central cover material, which requires a sewing machine designed to sew those two materials together curvilinearly along their respective curved end portions.
Some automated sewing devices enabling such curvilinear sewing are known. For example, the U.S. Pat. No. 5,544,602 discloses an automated sewing device comprising a movable guide plate having some guide rollers provided on the reverse side thereof and some guide grooves formed in a table on which a sewing machine is mounted. In this prior art, the guide rollers are movably fitted in the guide grooves so that the movable guide plate can be moved along a predetermined path, thereby causing a curved end portion of central cover material placed on the guide plate to be automatically sewn by the sewing machine with and along a curved end portion of peripheral cover material being fed toward the sewing machine.
However, such prior-art automated sewing device has been found defective in that it is troublesome for a worker to securely set the central cover material in position on the guide plate, and further, it is quite annoying labor for the worker to replace the guide rollers and guide grooves by different shapes of guide rollers and grooves according to a size and contour of each different central cover material as well as to a curvature of the curved end portion of the central cover material.
In particular, some of trim cover assemblies for automotive seats use one unitary sheet of thin contractible elastic material in the central cover section thereof. A typical material used in such central cover section is a Tricot knit fabric material or the like. This sort of thin contractible material, when it is cut and trimmed into a predetermined shape of central cover material corresponding to the central cover section of trim cover assembly, naturally tends to curl at the localized end portions thereof into a generally “U” shaped cross-section, as shown in FIG. 10 for example. When such thin material is sewn with other material, a worker needs to feed and stretch it with his or her hands to prevent the materials from natural curling at the peripheral ends thereof, thus resulting in troublesome labor on the worker's part and a poor efficiency for mass production of the trim cover assemblies.